Wireless communications handoff method and system employing such

ABSTRACT

A method for reducing a delay in a wireless communications system resulting from a handoff while mitigating a risk of premature termination of wireless communications, the method includes comparing data indicative of actual use of the wireless communications systems to at least one predetermined criteria. If the comparing determines a sector pairing in the wireless communications system to be statistically significant for purposes of recommending at least one search window setting, at least one value related with a distance associated with the sector pairing may be used to automatically determine a corresponding signal delay. If the corresponding signal delay exceeds a prior determined signal delay, a recommended search window setting may be determined using the corresponding signal delay.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 10/350,162 filed Jan. 23, 2003, entitled “WirelessCommunications Handoff Method and System Employing Such” which claimspriority to U.S. Provisional Application 60/351,325, filed Jan. 23,2002. The disclosure of the prior applications are considered part of(and are incorporated by reference in) the disclosure of thisapplication.

FIELD OF THE INVENTION

The present invention relates generally to wireless communications, andparticularly to handoff methods utilized in wireless communicationsnetworks.

BACKGROUND OF THE INVENTION

Many wireless communications networks utilize base stations eachpositioned to cover a corresponding “cell” within which a wirelesscommunications device may operate. As used herein, the term “wirelesscommunications device” generally refers to any device being suitable forcommunicating in a wireless fashion using a wireless communicationsnetwork. Examples of such devices include, but are not limited to:wireless telephones, i.e., handsets, and mobile computing devicesincluding such functionality, such as portable Personal Computers (PCs)and Personal Digital Assistants (PDAs). Further, each cell may bedivided into “sectors” as is also well understood.

A cell typically covers a limited geographic area and routescommunications between wireless communications devices physicallylocated within the limited geographic area and a telecommunicationsnetwork, such as a Public Switched Telephone Network (PSTN). When awireless communications device physically moves from one cell and/orsector to another, a “handoff” may be performed to coordinate operationof the wireless communications device with the new cell and/or sector.Generally, a handoff typically involves negotiating instructions betweenthe moving wireless communications device and one or more base stationsand/or mobile switching centers corresponding to the location of thewireless communications device. This serves to keep a communicationssession, such as a phone call, active as the wireless communicationsdevice traverses from one cell and/or sector to another. A handoff maybe triggered, for example, when the wireless communications devicedetects a pilot signal from a different base station that exceeds agiven threshold.

Referring now to FIG. 1, there is shown an illustration of a handoffthreshold example for a CDMA system as a plot of pilot signal strengthversus time. At time (1), as the pilot signal strength 10 exceeds athreshold T_ADD, the mobile communications device sends a Pilot StrengthMeasurement Message and transfer the pilot to a Candidate Set 20. Attime (2), the corresponding base station sends a Handoff DirectionMessage. At time (3), the mobile communications device transfers thepilot to the Active Set 30 and sends a Handoff Completion Message. Attime (4), as the pilot signal strength 10 drops below a thresholdT_DROP, the mobile communications device starts a handoff drop timer. Attime (5), the handoff drop timer expires, and the mobile communicationsdevice sends a Pilot Strength Measurement Message. At time (6), thecorresponding base station sends a Handoff Direction Message. At time(7), the mobile communications device moves the pilot from the ActiveSet 30 to the Neighbor Set 40 and sends a Handoff Completion Message.This technique is well understood by those possessing an ordinary skillin the pertinent art.

In a wireless communications network utilizing a Code Division MultipleAccess (CDMA) system, a handoff from one cell and/or sector to anotherinvolves estimating the timing of a received signal. Wirelesscommunications devices communicating via CDMA systems may experiencedelays in reception of signals due to the speed of light, reflections,and mobility of the wireless communications devices. When a wirelesscommunications device moves from a first cell to a second cell, ahandoff is performed to assign new system resources associated with thesecond cell. CDMA systems may employ “Search Windows” of a settablelength over which to search for the potentially delayed signals. ASearch Window is typically set around spreading (or PseudoRandom—PN)sequence phase offsets where geographically adjacent base stations areexpected to be transmitting. If a utilized Search Window is set toowide, the searching process can temporally delay handoffs, reducingperformance of the wireless communications devices and capacity of thenetwork system. Further, if the Search Window is set too narrow,wireless communications devices may not acquire delayed signals, whichmay lead to poor performance and dropped communications, such as calls,due to one or more missed handoff opportunities.

Conventionally, two methods for setting Search Windows may be employed:default settings may be used based upon general manufacturerrecommendations; or vehicles with test equipment may be moved throughoutthe cells and sectors and used to collect timing delay information tocalculate Search Window settings.

The first method may prove satisfactory for many handoff scenarios, buttypically does not provide for even nearly-optimal settings. The secondmethod can provide improved performance over the first method, but, isoften expensive, time-consuming, and typically requires large areas tobe covered in the data collection process—further driving up costs inboth dollars and time.

SUMMARY OF THE INVENTION

A method for reducing a delay in a wireless communications systemresulting from a handoff while mitigating a risk of prematuretermination of wireless communications, the method including: comparingdata indicative of actual use of the wireless communications systems toat least one predetermined criteria; if the comparing determines asector pairing in the wireless communications system to be statisticallysignificant for purposes of recommending at least one search windowsetting, using at least one value related with a distance associatedwith the sector pairing to automatically determine a correspondingsignal delay; and, if the corresponding signal delay exceeds a priordetermined signal delay, determining a recommended search window settingusing the corresponding signal delay.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be better understood with reference to the followingillustrative and non-limiting drawings, wherein like references identifylike elements of the invention, and:

FIG. 1 illustrates a handoff threshold example for a CDMA system as aplot of pilot signal strength versus time;

FIG. 2 illustrates a flow diagram of a method according to an aspect ofthe present invention;

FIG. 3 illustrates a flow diagram of a method according to an aspect ofthe present invention; and,

FIG. 4 illustrates a flow diagram of a method according to an aspect ofthe present invention.

DETAILED DESCRIPTION OF THE PRESENT EMBODIMENTS

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for the purposes of clarity, many other elements and steps found intypical wireless communications systems and methods. Those of ordinaryskill in the art will recognize that other elements and steps aredesirable and/or required in order to implement the present invention.However, because such elements and steps are well known in the art, andbecause they do not facilitate a better understanding of the presentinvention, a discussion of such elements and steps is not providedherein.

For sake of explanation, the present invention will be discussed as itrelates to wireless communications systems and methods employing CDMAand as it relates to handsets. However, it will be well understood bythose possessing an ordinary skill in the pertinent arts that otherwireless communications devices and wireless communications systems andmethods utilizing Search Windows can be adapted to incorporate thepresent invention as well. Examples of other wireless communicationssystems and methods include, but are not limited to, other multipleaccess techniques such as Wideband CDMA (WCDMA), Time Division MultipleAccess (TDMA) and Frequency Division Multiple Access (FDMA), as well asother wireless technologies such as Global System for MobileCommunications (GSM) systems and Advance Mobile Phone Service (AMPS)systems.

Many wireless communications system infrastructures, such as thoseemploying CDMA, provide detailed statistical information on handoffsoccurring between sectors within a system or collection of systems. Thehandoff information can be used to set the “Neighbor Lists”, e.g.,“Neighbor Sets”, for each sector. Neighbor Lists are used so wirelesscommunications devices using the system, e.g., handsets, can identifywhich sectors to search for in the handoff process, in conjunction withthe Search Windows. According to an aspect of the present invention, thehandoff information and the locations of sectors can be used to estimatean improved Search Window setting.

Referring now to FIG. 2, there is shown a flow diagram of a method 100suitable for setting a Search Window according to an aspect of thepresent invention. First, a distance between a sector for which thesetting is being determined (the “reference sector”) and another sector(the “target sector”) may be determined 110. According to an aspect ofthe present invention, a statistically significant target sector can beidentified as having a minimum percentage of handoffs that occur withthe “target sector” to the total handoffs by the reference sector.

A select “target” sector that is both statistically significant inhandoffs and geographically farthest away from the reference sector maythen be determined 120. Of course, other target sectors may bedetermined as a select target sector as well.

A timing delay for the select target sector may then be calculated 130using a distance corresponding to a distance between the reference andtarget sectors. This may be accomplished using well known techniques andthe speed of light, for example.

An estimate 140 of signal delay caused by signals between the referenceand select target sectors reflecting off of distant objects may then bemade. Again, this estimation can be accomplished using well knownconventional techniques.

A search window may then be determined 150 by adding the determinedtiming and estimated signal delays, and referencing an appropriateSearch Window setting as described in the CDMAOne (TIA/EIA/IS-95)Standard, for example. The entire disclosure of the CDMAOne standard ishereby incorporated by reference as if being set forth in its entiretyherein. Of course, other standards, such as 1XRTT could be utilized aswell as, or in lieu of, the CDMAOne standard.

A reduction factor can then be applied 160 to the calculated delaydepending on well known factors, such as geographic topography or sectorlayout within the system, for example. The reduction factor may bedefined as a percentage reduction in delay, for example. Again, suchreductions are well understood by those possessing an ordinary skill inthe pertinent arts.

The reduced, calculated search window can then be defined 170 as aminimum search window setting for a collection of sectors including thereference and target sectors, and/or the wireless communications system,for example. This provides a search window setting recommendation thatis substantially optimized for each sector in the collection, or systemfor example. As will be readily understood by those possessing anordinary skill in the pertinent arts, such a defined minimum searchwindow setting should reasonably ensure that handoffs occur with areduced delay, yet avoid non-detection of delayed signals.

According to an aspect of the present invention, one or more computerprograms, e.g., sequence of operational steps in a machine readablelanguage or form, can be used in combination with any suitable computingdevice or combination of devices to perform the method. The one or morecomputer programs can be stored using any suitable computer readablemedium. Further, the computing devices may include, or further utilize,one or more computer readable mediums including data to be used by theone or more computer programs, such as data indicative of an appropriateSearch Window setting as described in the CDMAOne (TIA/EIA/IS-95)Standard and above and/or one or more of the reduction factors, forexample.

According to an aspect of the present invention, the present method,and/or one or more computer programs, may be instantiated one or moretimes, either in response to a user request therefore, or automaticallybased upon one or more criteria. Exemplary criteria include, but are notlimited to, changes in one or more reduction factors, changes in datautilized and/or at predetermined temporal intervals, for example.

Referring now to FIG. 3, there is illustrated a flow diagram of a method200 according to an aspect of the present invention. The method 200 ofFIG. 3 will be discussed with reference to Table-1. As will be readilyunderstood by those possessing an ordinary skill in the pertinent art,Table-1 illustrates a portion of a larger table, which may be preparedusing a commercially available spreadsheet program, such as MicrosoftExcel. The illustrated Table-1 has been limited to analyze a single cell1 having three sectors, A, B and G for sake of clarity.

TABLE 1 MAX. R. CELL R. SEC. T. CELL T. SEC. HO FWD. HO REV. HO % FWD.CUM % FWD DIST. (KM) CHIPS CHIPS (300) (305) (310) (315) (320) (325)(330) (335) (340) (345) (350) 1 A 36 G 2566 4013 28.08 28.08 4.2387467697 7 1 A 46 B 1669 1191 18.26 46.34 4.26919653 7 7 1 A 1 G 843 3996 9.2355.57 0 0 7 1 A 1 B 694 1815 7.59 63.16 0 0 7 1 A 104 A 673 357 7.3670.53 4.553619534 7 7 1 A 46 G 666 747 7.29 77.82 4.26919653 7 7 1 A 17B 591 156 6.47 84.29 6.780116522 8 8 1 A 36 A 337 486 3.69 87.974.238746769 7 8 1 A 116 B 212 182 2.32 90.29 5.057733638 8 8 1 A 115 A146 268 2.06 92.35 7.115110949 8 8 1 A 105 B 181 152 2 94.35 6.4901395858 8 1 A 39 G 142 466 1.55 95.91 7.104659383 8 8 1 A 36 B 89 821 0.9796.88 4.238746769 7 8 1 A 5 B 83 3 0.93 97.81 8.679315764 9 8 1 A 100 A57 479 0.62 98.44 2.982138282 6 8 1 A 5 A 53 2 0.58 99.02 8.679315764 98 1 A 116 A 31 18 0.34 99.35 5.057733638 8 8 1 A 39 B 28 66 0.31 99.667.104659383 8 8 1 A 68 B 10 81 0.11 99.77 7.006377342 8 8 1 A 41 G 6 90.07 99.84 6.687386515 8 8 1 A 3 G 4 1 0.05 99.89 8.597521298 9 8 1 A 40G 2 1 0.02 99.91 11.32394623 10 8 1 A 46 A 2 19 0.02 99.93 4.26919653 78 1 A 124 A 2 3 0.02 99.96 10.43178857 10 8 1 A 105 G 1 0 0.01 99.976.490139585 8 8 1 A 17 A 1 4 0.01 99.98 6.780116522 8 8 1 A 104 G 1 00.01 99.99 4.553619534 7 8 1 A 41 A 1 0 0.01 100 6.687386515 8 8 1 A 5 G0 1 0 100 8.679315764 9 8 1 A 39 A 0 2 0 100 7.104659383 8 8 1 A 68 G 02 0 100 7.006377342 8 8 1 A 116 G 0 1 0 100 5.057733638 8 8 1 A 68 A 0 50 100 7.006377342 8 8 1 A 124 B 0 1 0 100 10.43178857 10 8 1 A 100 G 0 10 100 2.982138282 6 8 1 A 17 G 0 3 0 100 6.780116522 8 8 1 A 53 B 0 1 0100 8.821774911 9 8 1 A 124 G 0 1 0 100 10.43178857 10 8 1 A 53 A 0 0 0100 8.821774911 9 0 1 B 1 G 4354 4307 26.57 26.57 0 0 0 1 B 100 A 30012500 18.31 44.88 2.982138282 6 7 1 B 104 G 1986 990 12.12 57 4.5536195347 7 1 B 1 A 1815 694 11.08 68.08 0 0 7 1 B 100 G 1179 951 7.19 75.272.982138282 6 7 1 B 125 A 1177 1041 7.18 82.46 10.67026533 10 10 1 B 46G 696 248 4.41 86.87 4.26919653 7 10 1 B 36 G 537 301 3.28 90.144.238746769 7 10 1 B 17 B 404 331 2.6 92.74 6.780116522 8 10 1 B 104 A425 312 2.59 95.34 4.553619534 7 10 1 B 82 G 205 557 1.25 96.598.351849252 9 10 1 B 68 B 185 55 1.17 97.76 7.006377342 8 10 1 B 100 B131 246 0.8 98.56 2.982138282 6 10 1 B 108 G 84 53 0.51 99.079.766789214 10 10 1 B 39 G 32 14 0.2 99.27 7.104659383 8 10 1 B 116 B 249 0.19 99.46 5.057733638 8 10 1 B 33 G 18 10 0.11 99.57 7.562384801 9 101 B 31 G 16 10 0.1 99.66 11.56147212 10 10 1 B 46 B 15 15 0.09 99.764.26919653 7 10 1 B 134 A 14 10 0.09 99.84 16.71266896 12 10 1 B 125 B 830 0.05 99.89 10.67026533 10 10 1 B 82 A 5 6 0.03 99.92 8.351849252 9 101 B 104 B 4 5 0.02 99.95 4.553619534 7 10 1 B 36 B 3 5 0.02 99.964.238746769 7 10 1 B 124 A 2 0 0.01 99.98 10.43178857 10 10 1 B 105 B 20 0.01 99.99 6.490139585 8 10 1 B 82 B 1 1 0.01 99.99 8.351849252 9 10 1B 17 A 1 2 0.01 100 6.780116522 8 10 1 B 125 G 0 10 0 100 10.67026533 1010 1 B 46 A 0 1 0 100 4.26919653 7 10 1 B 135 A 0 1 0 100 19.58037433 1310 1 B 57 G 0 0 0 100 10.05361698 10 10 1 B 116 A 0 0 0 100 5.0577336388 10 1 B 57 A 0 0 0 100 10.05361698 10 10 1 B 57 B 0 0 0 100 10.0536169810 10 1 B 124 B 0 0 0 100 10.43178857 10 10 1 G 1 B 4307 4354 18.7218.72 0 0 0 1 G 100 A 4155 2311 18.06 36.77 2.982138282 6 6 1 G 1 A 3996843 17.36 54.13 0 0 6 1 G 68 B 2264 3925 9.84 63.97 7.006377342 8 8 1 G17 B 1939 3557 8.43 72.4 6.708116522 8 8 1 G 46 G 1798 965 7.81 80.214.26919653 7 8 1 G 36 G 963 922 4.18 84.4 4.238746769 7 8 1 G 17 A 832753 3.62 88.01 6.780116522 8 8 1 G 46 A 518 1118 2.25 90.26 4.26919653 78 1 G 104 G 393 162 1.85 92.11 4.553619534 7 8 1 G 100 G 405 332 1.7693.87 2.982138282 6 8 1 G 124 A 368 283 1.6 95.47 10.43178857 10 10 1 G116 G 366 195 1.59 97.06 5.057733638 8 10 1 G 104 A 259 31 1.19 98.254.553619534 7 10 1 G 39 G 143 38 0.67 98.92 7.104659383 8 10 1 G 68 G104 280 0.45 99.37 7.006377342 8 10 1 G 125 A 92 130 0.44 99.8110.67026533 10 10 1 G 116 B 21 6 0.09 99.9 5.057733638 8 10 1 G 46 B 747 0.03 99.93 4.26919653 7 10 1 G 82 G 4 6 0.02 99.95 8.351849252 9 10 1G 124 G 3 142 0.01 99.97 10.43178857 10 10 1 G 98 A 2 0 0.01 99.9710.28754167 10 10 1 G 82 A 2 1 0.01 99.98 8.351849252 9 10 1 G 134 A 1 00 99.99 16.71266896 12 10 1 G 100 B 1 2 0 99.99 2.982138282 6 10 1 G 5 B1 2 0 100 8.679315764 9 10 1 G 105 B 1 3 0 100 6.490139585 8 10 1 G 115A 0 5 0 100 7.115110949 8 10 1 G 124 B 0 5 0 100 10.43178857 10 10 1 G68 A 0 8 0 100 7.006377342 8 10 1 G 17 G 0 42 0 100 6.780116522 8 10 1 G36 A 0 1 0 100 4.238746769 7 10

According to an aspect of the present invention, reference cells andsectors of a wireless communications system may be selected for analysis210. The cells and sectors chosen may be a subset of all cells andsectors in the system or may include all, or substantially all, of thecells and sectors in the system. Reference cells chosen for analysis areillustrated in column 300 of Table 1, while reference sectors are shownin column 305. In the illustrated example, analysis of only a singlecell 1, having three sectors (A, B and G) is shown for purposes ofclarity. Of course, in practicing the present invention more than onecell, each having a suitable number of sectors, may be analyzed.

Target cells and sectors may be determined 215. The target cells chosenfor analysis are illustrated in column 310 of Table 1, while the targetsectors are shown in column 315.

A number of handoffs between each selected reference cell to eachdetermined target cell may then be determined 220. This may beaccomplished using any suitable technique. For example, data indicativeof these handoffs may be provided by the wireless networkinfrastructure, such as by switches for example. Alternatively, thehandoffs may be estimated using techniques understood by thosepossessing an ordinary skill in the pertinent arts. Data indicative ofthe forward handoffs (from reference to target) is illustrated in column320 of Table 1, while data indicative of reverse handoffs (from targetto reference) is shown in column 325.

A percentage of the total handoffs for the reference cell and sectorthat the determined number of forward handoffs (from the target to thereference) comprise may then be determined 225. Again, this may beaccomplished using any suitable technique. For example, data indicativeof these handoffs may be provided by the wireless networkinfrastructure, such as by switches for example. Alternatively, thesepercentages may be estimated using techniques understood by thosepossessing an ordinary skill in the pertinent arts. Data indicative ofthe percentage that these forward handoffs (from reference to target)make up of the total number of handoffs for the cell and sector isillustrated in column 330 of Table 1. Data indicative of the cumulativeof percentages illustrated in column 330 for each cell and sector isillustrated in column 335 of Table 1.

As set forth, the determining whether a sector-sector pairing isstatistically significant can be accomplished using any suitabletechnique. For example, if the total number of forward handoffs betweenthe sector-sector pairing exceeds a given threshold percentage of thetotal handoffs for the reference sector, such as one percent forexample, the sector-sector pairing can be determined to be statisticallysignificant. This percentage may further be variable, rather than fixed.For example, of the average neighbor list size exceeds a threshold, suchas when approaching twenty for example, the percentage may be increased,such as to one and one-half percent, for example. Analogously, if anaverage neighbor list size is below a given threshold, the percentagemay be decreased, such as to one-half percent, for example. Of course,any suitable percentage as determined by one having an ordinary skill inthe art, may be utilized.

As set forth above, a distance between the reference and target cellsand sectors may determined 225 using any suitable technique. Forexample, where each cell and sector is at a known geo-location, thedistance measurements can be performed automatically using well knowntechniques and data indicative of these geo-locations. Data indicativeof the distances determined is illustrated in column 340 of Table-1.

The distance determined 225 may then be converted 230 into a number ofchips indicative of symbol delay in communications associated with thereference and target cells and sectors as is well understood by thosepossessing an ordinary skill in the pertinent art. Again, this may beaccomplished automatically using well known algorithms. Data indicativeof a number of chips corresponding to the distances determined 225 isshown in column 345 of Table-1. According to an aspect of the presentinvention, the distance converted may correspond to the actual distancedetermined between the sectors, e.g., between towers as determined bytheir respective geo-locations. According to an aspect of the presentinvention, the distance converted may correspond to an actual distancebetween sectors having a scaling factor applied to it. The appliedscaling factor may be greater or less than 1, such as 0.8 or 1.2, forexample).

If a reference and target cell and sector pairing is determined to havea statistically significant number of handoffs, using the percentagesdetermined in step 225 for example, and the converted chips 230 exceedsa previously determined maximum chip count, then the converted 230 chipscan be used to determine, i.e., ratchet up, 235 a maximum chip count. Ifthe target cell and sector pairing is determined not to have astatistically significant number of handoffs, and/or the converted chips230 do not exceed a previously determined maximum chip count, theconverted chips can be disregarded for purposes of setting the maximumchip count. Data indicative of a maximum chip count is shown in column350 of Table-1.

The maximum chip count determined 235 can then be used, in combinationwith an appropriate Search Window to set a minimum search window 240 ashas been discussed with regard to FIG. 2.

Referring now to FIG. 4, there is illustrated a flow diagram of a method300 according to an aspect of the present invention. According to anaspect of the present invention, a search window setting can berecommended so as to reduce a delay in a wireless communications systemresulting from a handoff while mitigating a risk of prematuretermination of wireless communications.

According to an aspect of the present invention, statistical datacompiled using, and indicative of, actual subscriber use (collected by aswitch or other network device, for example) may be used to determinestatistically significant pairings of sectors. As will be readilyunderstood by those possessing an ordinary level of skill in the art,the data can be collected, compiled and/or provided using a wirelesscommunications system switch, or any other suitable device collectingand/or compiling data indicative of actual user information. For sake ofclarity, the present disclosure is by way of the amount of handoffsoccurring between each sector on a hourly, daily, weekly, or othertimeframe basis to determine statistical significance, for example. Ofcourse, other types of information collected using the network, and notjust handoff information, may be utilized in lieu of, or in addition to,handoff information.

According to an aspect of the present invention, data output from atleast one switch in the wireless communications system may be compared310 to at least one predetermined criteria, such as a threshold, so asto determine whether a sector pairing in the wireless communicationssystem (e.g., reference sector-target sector pairing) is statisticallysignificant for purposes of setting a search window. If the sectorpairing is statistically significant 320, at least one value relatedwith a distance associated with the sector pairing, such as a distancebetween towers which may or may not have a scaling factor applied to it,may be used to determine 330 a corresponding signal delay. If thecorresponding signal delay exceeds a prior determined signal delay 340,corresponding to another sector pairing for example, a search windowsetting may be recommended 350 using the corresponding signal delay.

Although the invention has been described and pictured in a preferredform with a certain degree of particularity, it is understood that thepresent disclosure of the preferred form has been made by way ofexample, and that numerous changes in the details of construction andcombination and arrangement of parts and steps may be made withoutdeparting from the spirit and scope of the invention as is hereinafterclaimed.

1. A method for reducing a delay in a wireless communications systemresulting from a handoff while mitigating a risk of prematuretermination of wireless communications, said method comprising:identifying a plurality of communications sectors, each of said sectorshaving a geographic relationship with respect to each other of saidsectors; automatically selecting two of said sectors based upon saidgeographic relationship, wherein a number of handoffs between theselected sectors exceeds a threshold; automatically determining awireless communications timing delay for said selected sectors;automatically estimating a signal delay for said selected sectors; andrecommending a search window associated with the selected sectors inresponse to determining that the estimated signal delay exceeds apredetermined signal delay.
 2. The method of claim 1, whereinrecommending a search window further comprises summing said determinedtiming delay and said estimated signal delay.
 3. The method of claim 2,further comprising comparing said summed timing and signal delays topredetermined criteria.
 4. The method of claim 2, further comprisingusing at least one reduction factor to reduce said summed delays.
 5. Themethod of claim 4, wherein said reduction factor is at least partiallybased upon a geographic topography.
 6. The method of claim 4, whereinsaid reduction factor is at least partially based upon a layout of atleast some of said plurality of sectors.
 7. A non-transitory computerreadable medium encoded with instructions for recommending a searchwindow setting, the instructions being operable to cause data processingapparatus to perform operations comprising: identifying a referencesector and a target sector that together comprise a sector pairingassociated with a wireless communications system, wherein a number ofhandoffs associated with the sector pairing exceeds a threshold;determining, for the sector pairing, a search window based on a timingdelay and an estimated signal delay associated with the sector pairing;generating a reduction factor; and recommending a reduced search windowbased on the determined search window and the reduction factor.
 8. Thecomputer readable medium of claim 7, wherein the target sectorrepresents a sector in the wireless communications system having agreatest distance from the reference sector for which the number ofhandoffs associated with the resulting sector pairing exceeds thethreshold.
 9. The computer readable medium of claim 7, wherein thereduction factor is based on a sector layout within the wirelesscommunications system.
 10. The computer readable medium of claim 7,wherein the reduction factor represents a percentage reduction in thetiming delay and the estimated signal delay.
 11. The computer readablemedium of claim 7, wherein the instructions are further operable tocause data processing apparatus to perform operations comprising:defining the reduced search window as a minimum search window settingcorresponding to at least the reference sector and the target sector.12. The computer readable medium of claim 7, wherein the number ofhandoffs associated with the sector pairing comprises an estimatednumber of handoffs.
 13. The computer readable medium of claim 7, whereinthe instructions are further operable to cause data processing apparatusto perform operations comprising: determining the threshold based on anassociated neighbor list size.
 14. A system for recommending a searchwindow for use in a wireless communications system, comprising: awireless communications system including a plurality of sectors; andprocessor electronics configured to perform operations comprising:identifying, from the plurality of sectors, a sector pairing comprisinga reference sector and a target sector for which the number ofassociated handoffs represents at least a threshold percentage of atotal number of handoffs associated with the reference sector;determining a distance between the reference sector and the targetsector; converting the determined distance to a delay value indicating adelay in communications associated with the identified sector pairing;and generating a recommended search window in accordance with the delayvalue when the delay value exceeds a delay threshold.
 15. The system ofclaim 14, wherein the number of associated handoffs represents thenumber of handoffs from the target sector to the reference sector. 16.The system of claim 14, wherein the threshold percentage of the totalnumber of handoffs associated with the reference sector is a variablethreshold determined based on a neighbor list size.
 17. The system ofclaim 14, wherein the number of associated handoffs is determined basedon handoff data provided by one or more items of wireless networkinfrastructure.
 18. The system of claim 14, wherein the processorelectronics are further configured to perform operations comprising:applying a scaling factor to the determined distance in conjunction withconverting the determined distance to the delay value.
 19. The system ofclaim 14, wherein the number of associated handoffs is estimated. 20.The system of claim 14, wherein determining the distance between thereference sector and the target sector is performed automatically basedon known geo-location data corresponding to the reference sector and thetarget sector.